Helgö is an island in Ekerö Municipality in Stockholm County, Sweden. Helgö is an island situated in the lake Mälaren. The island's greatest width is about 1.5 km (0.9 mi), it is about 5 kilometres (3.1 miles) long and covers 48 hectares (119 acres). Excavations at Helgö The island is perhaps best known for a major archaeological area. The old trading town on Helgö began to emerge around the year 200 AD, 500 years before Birka at Björkö. The first archaeological dig in 1954 uncovered the remains of the early settlement, including a workshop area which attracted international interest.
https://en.wikipedia.org/wiki/Helg%C3%B6